In display technical field, a flat panel display as a liquid crystal display (LCD), an organic light emitting diode (OLED), and so forth is gradually substituted for cathode ray tube (CRT) monitor, and are applied to the liquid crystal display television, cell phone, personal digital assistant, calculator panel, or laptop panel.
A display panel is an important part of LCD or OLED; take LCD for example: the display panel is mainly composed of a thin film transistor (TFT) substrate, a color filter (CF) substrate, and a liquid crystal layer between the thin film transistor substrate and the color filter substrate; the working principles is that a driving voltage is applied to an transparent conductive electrode on the TFT substrate and the CF substrate to control the rotation of liquid crystal elements of the liquid crystal layer; furthermore, the light of a backlight module will be reflected to produce image, and the backlight provides different colors through the CF substrate; therefore, therefore, the performance of materials of the transparent conductive electrode has a great influence on the display effect.
Currently, a traditional transparent conductive film is an indium tin oxide (ITO) film manufacturing by Physical Vapor Deposition (PVD). The specific manufacturing process is that: in a PVD device, a strong current bombards ITO targets and a transparent conductive ITO film is deposited on the substrate. The properties of the transparent conductive ITO film are high light transmittance, high conductivity and stable structure. However, because it takes a long time in the manufacturing process, the resistance of the ITO is higher, and the film cannot show the bending characteristic at a certain external force according to physical properties of the ITO film thereof; therefore, it limits the applications in flexible panel and wearable device as well. It has important significance and value to seek high conductivity, high transmittance, simple manufacture method, and abound resource substitutes for ITO.
Poly-3,4-ethylenedioxythiophene/poly-styrenesulfonate (PEDOT:PSS) is a macromolecule polymer, and is largely applied in several areas as organic photovoltaic (OPV), organic field effect transistor (OFET), organic light-emitting diode (OLED) and flexible panel; a film formation with the macromolecule polymer has a high stability, high light transmittance and high conductivity; besides, the resistance of the ITO film can use distribution ratio adjustment to make widely windows, and be suitable for large-scaled flexographic printing. A study shows that adding few glycerol or sorbitol in PEDOT:PSS can obviously increase conductivity without losing light transmittance. Fullerene, such as C60 and C70, are allotrope of element carbon with a shape similar to a soccer and every carbon atom in SP2 hybridization mode achieves three-dimensional aromatic. Although the solubility of pure fullerence is poor, many type of soluble functional group are induced by chemically modified method and so the solubility of aqueous solution/organic solvent is increased without affecting conductivity. As an excellent carriers-transporting material, it can be used well in OPV, OFET, OLED and flexible device.